Stoker



EARLL R. STONE, 0F WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WES'JPINGHOUSEl ELECTRIC & MANUFACTURING CO., A CORPORATION 0F PENNSYLVANIA.

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Application led November 8, 1919. Serial No. 336,668.

To all lwlw/m, tf/nay concern.'

Be it known that' I, EARLL citizen of the United States. and a resident of vWilkinsburg5 in the county 'of Allegheny and State' of Pennsylvania, have made a new and useful Invention *in a Stoker, of which the following is a specification.

This invention relates to stokers and particularly to a new and improved fuel feeding apparatus for stokers.

The capacit of some stokers, particularly those of the c aingrate type, is limited by the relatively slow rate of combustion of the fuel. In the ordinary constructions ignition takes place at the surface and progresses downward into the fuel bed as the fuel passesthrough the furnace. This action is opposed by the draft or blast of relatively cool air coming up through the relatively cool fuel bed and consequently'combustion is retarded land the capacity of the stoker limited. Y

An object of my invention is to produce a new and improved fuel feeding arrangement for stokers whereby the rate of combustion of the fuel may be accelerated.

A further object is to produce a new and improved Stoker in which combustion occurs on the surface of the bed of fuel in one part of the stoker and Within the bed of fuel in another part of the stoker.

A further object is to produce a new and improved chain grate Stoker having a greater fuel burning capacity for a given grate area than other chain grate stokers now in use and known to me.

A further object is to produce a new and improved method of feeding fuel into a furnace whereby the sifting of fine fuel through the grate is substantially eliminated and a high rate of combustion obtained.

These and other objects which will be means of apparatus embodving the features herein described and illustrated in the drawing accompanying and forming a part. here- 0 D The drawingr is a diagrammatic sectional view of a stoker embodying my invention.

In the drawing Ihave illustrated a stoker 5 of the chain grate type as installed under a boiler 6. As shown, the stoker 5 is mounted on wheels 7 and rails 8 in such a manner that it may be moved into and out of opera- R. STONE, a f

tive relation .with the boiler 6. I have illustrated the stoker in operative position relai arch'12. With this arrangement the crosssectional area of the combustion space 11 increases from the front end of the Stoker toward the rear or boiler end, and therefore provides ample space for4 the cumulative volume of gases rising from the fuel bed. As illustrated, the stoker 5 comprises an endless chain grate 12 which is supported on a frame 13 and on suitable sprocket wheels 14 and 15 located -at'opposite ends of the frame. Power for operating the grate is ydelivered to the front sprocket wheel 14 by means of the worm 16 and the gear 17 this construction being familiar-to those skilled in the art and requiring no further description.

At the front end of the grate 12 I have shown a hopper 18 for delivering fuel to the grate. As illustrated, a gate 19 is provided and may be controlled or adjusted in any suitable manner, for example, by means of a crank 20 and suitable gearing 21, such as is frequently employed in ordinary chain grate Vstoker construction. -As illustrated, fuel is delivered to the hopper 18 by means of an inclined chute or spout 22. In the bottom of the spout 22 and at some distance from the hopper 18 I have shown ascreen 2 3 by means of which the fine fuel is sift'ed out of the mass of fuel coming down the spout 22. The fine fuel which passes through the screen 23 is collected and stored in an auxiliary hopper 24 which, as shown, islocated above the fire brick arch 12. As illustrated, the lower part of the hopper 24 terminates in a passage 25 located between the front and rear re brick arches 12l and 13a and extendingl across the chain grate 12 and opening into the combustion space 11. An agitator or fuel feeding device 26 is shown in the lower part of the hopper 24 for feeding the fine fuel into the passage 25. The fuel fed into the passage 25 drops on top of the fuel carried into the furnace from the front or main hopper 18 by the chain grate.

The feeding device illustrated is adapted to be driven by means of sprocket wheels 27 and a suitable chain 28, the lower sprocket wheel 2T being geared to the main sprocket wheel of the chain grate by means of suitable gears 29. Obviously, the speed of the feeding device will bear a definite relation to the speed of the chain grate l2and, if desired, the gears 29 may be so arranged that this relation of speeds may be varied to suit different operating conditions.

Stokers such as that illustrated may be operated either with natural draft or with forced or induced draft. ln the drawing, l have illustrated a forced draft arrangement comprising air boxes 30 located immediate? ly below the upper portion of the grate 12 and adapted to deliver air under pressure upwards through the grate and the fuel bed. The air may be delivered at different pressures from different air boXes so that the blast may be adjusted to suit the local thickness of the fuel bed. F or example, the intermediate boxes 3() may deliver air at a greater pressure or velocity than the end boxes, the fuel bed being thicker on the center portion of the grate than at either end and therefore oil'ers greater resistance to the flow of air.

In operation, the coarser fuel is delivered to the grate l2 by the spout 22 and the hopper 18. lt is ignited as it passes from under the gate 19 into the combustion space ll. flhe finer fuel is fed on top of the coarse fuel by means of the feeding device 26 as the grate carries coarse fuel under the passage 25. The lire is then in the middle portion of the fuel bed and combustion proceeds at a rapid rate.

A separate supply of fuel may be fed to each of the twohoppers 18 and 24, but coarse fuel is preferably delivered to the hopper 18, as it is more free burning than fine fuel and does not tend to sift through the gratef The finer fuel is preferably fed on top of the coarse fuel after the latter is well ignited, and is thereby effectively prevented from sifting. 'lhe arrangement illustrated ensures a tine distribution of the fuel fed on to the grate so that the tendency of the blast to form pockets in the fuel vbed is substantially eliminated.

llhile l have described and illustrated but one embodiment of my invention, it will be apparent to those skilled in the art that various changes, modifications, additions and omissions may be. made in the apparatus described and illustrated without departing from the spiritvand scope of the invention as set forth by the appended claims.

What l claim is:

l. ln a furnace having a progressive feed grate, the combination of an inclined fuel chute, a hopper associated therewith at an elevated position, a portion of the chute being perforated to forma screen adapted to deliver finer fuel to said elevated hopper, a second hopper at a lower level and in front of the elevated hopper and positioned to receive coarser fuel from the lower end of the chute and means associated with each hopper to distribute the fuel fed by the chute to non-contiguous portions of the grate.

ln a furnace having a progressive feed grate, the combination of a hopper at an elevated position and adapted to deliver fuel to an intermediate portion of the furnace grate, a second hopper at a lower level and in front of the elevated hopper and adapted to deliver fuel to an end portion of the furnace grate, an inclined fuel chute adapted to supply fuel to the hoppers, and means provided in said chute to deliver fine fuel to the elevated hopper and coarsefuel to the lower hopper. i

3. ln a furnace in which the fuel is fed at non-contiguous places along a progressive feed grate, the combination of an elevated hopper, a second hopper disposed in front of and below the elevated hopper, an inclined fuel chute adapted to supply fuel t0 each hopper, a screen in said chute so disposed with relation to the elevated hopper as to deliver tine fuel to the elevated hopper, and means associated with each hopper to control the rate of distribution of fuel onto the said non-contiguous portions of the grate.

fl. ln a furnace having a progressive feed grate in which fuel is fed on the grate at noncontiguous places, the combination of an elevated hopper, a second hopper disposed in front of and below the elevated hopper, an inclined fuel chute supported by the elevated hopper and extending into the second hopper, means associated with the chute and the elevated hopper for separating the finer from the coarser fuel and delivering the liner fuel to the elevated hopper, and means associated with each hopper to control the rate of distribution of fuel onto the vnoncontiguous portions of the furnace grate.

ln testimony whereof, l have hereunto subscribed my name this seventh day of November, 1919.

EARLL R. STONE. 

